Differential scanning calorimetric measurements are being performed on LYLA-1, the chimera of human lysozyme and a-lactalbumin. In this chimera, the calcium binding loop of lactalbumin has been substituted for the corresponding regions in lysozyme. The thermodynamics of the conformational stability of both lysozyme and lactalbumin has previously been determined and reveals dramatic differences in the stability and unfolding behaviour. DSC analysis of LYLA1 in the presence and absence of Ca and as a function of pH will provide insights into the role of the calcium binding region in the stability of lactalbumin.